This invention, relates to a packaged synthetic absorbable suture having improved out of package handling characteristics and to a method of packaging polymeric articles having an inherent tendency to undergo degradation when exposed to water or a humid atmosphere, probably as a result of hydrolysis. More particularly, the invention is directed to improving the out of package flexibility and hand of synthetic absorbable sutures and to the packaging of articles and devices such as absorbable surgical sutures, clips, staples, implants, prostheses and the like, fabricated from polymers which are susceptible to hydrolytic degradation, notably, polymers and copolymers of glycolic acid (i.e., hydroxyacetic acid), the cyclic dimer of glycolic acid ("glycolide"), lactic acid, the cyclic dimer of lactic acid ("lactide") and related monomers, polydioxanone, polytrimethylene carbonate, polyalkylene glycol, polycaprolactone, their copolymers, etc. Polymers and copolymers of the foregoing kind and absorbable surgical devices made therefrom are well known. See, e.g. U.S. Pat. Nos. 2,668,162; 2,703,316; 2,758,987; 3,225,766; 3,297,033; 3,422,181; 3,531,561; 3,565,869; 3,620,218; 3,626,948; 3,636,956; 3,736,646; 3,772,420; 3,773,919; 3,792,010, 3,797,499, 3,839,297; 3,867,190; 3,878,284; 3,982,543, 4,060,089, 4,137,921; 4,157,437; 4,234,775; 4,237,920; 4,300,565; and 4,523,591; U.K. Patent No. 779,291; D. R. Gilding at al., "Biodegradable polymers for use in surgery--polyglycolic/poly(lactic acid homo- and co-polymers: 1, Polymer , Volume 20, pages 1459-1464 (1979), and D. F. William (ed.), Biocompatibility of Clinical Implant Materials, Vol. II, ch. 9: "Biodegradable Polymers" (1981). The biodegradability of these polymers/copolymers is believed to be due to the hydrolytic attack of their ester linkages by aqueous body fluids although the exact mechanism involved has been a matter of speculation. The present invention also extends to other surgical articles such as sutures based in whole or in part on a polyester polymer or copolymer such as polyglycolic acid, lactide-glycolide copolymer polydioxanone, polytrimethylene carbonate, polyalkylene glycols polycaprolactone, their copolymers etc.
Numerous patents, including U.S. Pat. Nos. 3,636,956; 3,728,639; 3,839,297; and 4,135,622 teach that synthetic absorbable surgical elements, particularly sutures, must be packaged and maintained under extremely dry conditions in order to be storage stable. Indeed, the preferred packaging and storage conditions described in the foregoing patents and used for commercially available synthetic absorbable sutures have a moisture level at or less than about 0.05% by weight of the suture, and preferably no more than about 0.02%. According to the patents, such conditions are attained by heating the suture and package to a high temperature under vacuum immediately prior to sealing, such as by heating to 180-188.degree. F. for 1 hour under a 26 inch vacuum. U.S. Pat. Nos. 4,412,617 and 4,519,501 are consistent. The latter patents disclose a package for synthetic absorbable ligating clips packaged under the aforementioned extremely dry conditions and further including a pro-dried paper dessicant. In addition, synthetic absorbable staples and clips made primarily of lactide have been available for several years from U.S. Surgical Corporation, Norwalk, Conn. Such clips and staples are not as susceptible to hydrolysis as other commercially available absorbable surgical materials, and are not packaged under the very dry conditions described in any of the foregoing U.S. Patents, but rather are packaged in foil envelopes including a dessicant, such as a silica pouch. U.S. Pat. No. 3,382,141 discloses a dessicant paper.
Synthetic absorbable sutures typically are packaged in moisture impervious foil laminate envelopes with the suture wound in a so-called "figure 8" pattern on a paper card retainer. Typical retainers are shown in U.S. Pat. No. 4,249,656 entitled "Suture Package"; U.S. Pat. No. 4,253,563 entitled "Multistrand Suture Package"; and U.S. Pat. No. 4,0630638 entitled "Direct Dispensing Packaging of Surgical Sutures." Longer lengths of such sutures or ligatures are sold on a suture reel, such as disclosed in U.S. Pat. Nos. 3,648,949 and 3,749,238. Unfortunately, heretofore known synthetic absorbable sutures packaged under very dry conditions are relatively stiff and inflexible. Such sutures typically exhibit "memory" which causes the suture to retain and have a tendency to resume the figure 8 or coiled shape assumed by the packaged suture. The figure 8configuration has also been found to introduce undesirable kinks and bends in the suture. These effects are highly undesirable since the suture must be straightened prior to use, and does not exhibit particularly good "feel" or "hand" characteristics important to the end user.
Molded suture packages having convoluted passageways are also known. By way of example, U.S. Pat. No. 3,338,401 entitled "Molded Suture Package" and U.S. Pat. No. 3,490,292 entitled "Method of Packaging Sutures" disclose a molded suture package wherein one or more elongated sutures are contained in a coiled narrow passageway having a plurality of convolutions. The foregoing patents teach that the suture may be drawn into the passageway by vacuum. The convoluted passageway desirably eliminates the introduction of kinks and bonds to the suture but, despite the desirable characteristics of molded suture packages, such packages have not been adopted for use in packaging synthetic absorbable sutures. It is speculated that the extremely dry conditions required for packaging prior synthetic absorbable sutures, together with the suture memory effect such very dry packaging conditions create, may combine to make it impossible to withdraw prior synthetic absorbable sutures from a molded suture package without breaking the suture.
Therefore, it would be highly desirable to provide a packaged synthetic absorbable suture having superior flexibility, "hand" and "feel" when removed from the package.
Accordingly, it is one object of the invention to provide a synthetic absorbable suture having improved out of package flexibility and hand.
It is a further object of the invention to provide a synthetic absorbable suture which does not exhibit undesirable memory effects.
Yet a further object of the invention is to provide a packaged synthetic absorbable suture which is more convenient to remove from the package.
Another object of the invention is to provide an improved package for sterile synthetic absorbable surgical elements.
Yet another object of the invention in to provide a packaged sterile synthetic surgical element which need not be packaged under extremely dry conditions.
These and other highly desirable and unusual results are accomplished by the present invention in a packaged synthetic absorbable suture which is amazingly supple, consistently easy to withdraw from the package, and, as removed from the package, does not exhibit memory or sets and has highly desirable out of package handling characteristics. The suture need, not be packaged under extremely dry conditions.
Objects and advantages of the invention am set forth in part herein and in part will be obvious herefrom or say be learned by practice with the invention, which is realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.
The invention consists of the novel parts, constructions, arrangements, combinations, steps, and improvements herein shown and described.